An in-flight aircraft may be subject to a direct strike of lightning, which injects high current pulses into the airframe. This event encompass both following categories of effects:                Direct attachment to the structure (local damage).        Transfer lightning current through the structure.        
These effects shall not lead to a hazardous situation compromising the continued safe flight and landing of the aircraft.
It is known that the aircraft protruding parts, areas called zone 1, are the most frequently struck by lightning. Rear locations of those aircraft parts, areas called zone 1B, experience the most severe ambient (2×105 Amp, energy of 2×106 Amp2 sec and charge transfer of 200 coulombs).
An Air-Air refueling operations consist in transferring fuel from a tanker aircraft to a receptor one. The function is performed by a conduit, which joins both aircrafts. Among others a telescopic refueling mast may be used.
Aircraft refueling masts are usually located at the rear part of the aircraft, therefore in the said lightning zone 1B.
Although refueling operation in stormy weather is not allowed, the tanker aircraft may be struck in its way to the operational area. For this purpose, at least, the telescopic refueling mast shall be protected against lightning in its retracted position.
Due to the nature of the telescopic mast (capable to be extended and retracted) the fuel conduct has sealing joints that will be stressed by lightning currents, causing arcing and sparking with energy (>200 uJ) enough to ignite fuel vapors.
One method of protection may be to electrically isolate the fuel conduit, so no arcing is expected since no lightning currents area allowed to flow inside. This means of lightning protection conflicts with the requirement to drain the static charge build-up caused by high-pressure fuel passage during refueling operation.
Accumulation of static charges may cause a danger of ignition of flammable vapors when uncontrolled discharges occur.
The present invention is intended to solve these drawbacks.